Aiming to stabilise the region and improve access for humanitarian workers, Annan had called officials from the UN Security Council's permanent members, the European Union, Egypt, Gabon and the Arab League to Thursday's one-day talks.
The AU also invited Libya, Nigeria, Rwanda, Senegal and South Africa.
Annan's fresh initiative came amid continuing violence in Darfur.
|The Darfur conflict has made millions homeless|
Before Thursday's meeting began, Sudanese rebels accused government troops and militias of killing more than 50 people in an attack on their positions in north Darfur.
Violence in Darfur has raged since 2003, with some 200,000 people killed and more than 2.5 million driven from their homes.
The head of one faction of the rebel Sudan Liberation Army [SLA] said government troops, backed by allied Janjaweed militia, attacked its positions in the Deir Mazza area on Wednesday, killing several rebels and the rest civilians.
The government had used fighter planes, Abdel Wahed al-Nur told Reuters, calling the attack "a massive escalation from the government" which would bring an SLA response.
A Sudanese army spokesman, who declined to be named, said the report was "100 per cent incorrect".